Class 12th

The surface of a metal is illuminated alternately with photons of energies E? = 4eV and E? = 2.5eV respectively. The ratio of maximum speeds of the photoelectrons emitted in the two cases is 2. The work function of the metal in (eV) is 

In the circuit, given in the figure currents in different branches and value of one resistor are shown. Then potential at point B with respect to the point A is:

A galvanometer is used in laboratory for detecting the null point in electrical experiments. If, on passing a current of 6 mA it produces a deflection of 2°, its figure of merit is close to:

The quantities x = 1/√(µ₀ε₀), y = E/B and z = 1/CR are defined where C-capacitance, R Resistance, l-length, E-Electric field, B-magnetic field and ε₀, µ₀, - free space permittivity and permeability respectively. Then:

What would be the electrode potential for the given half cell reaction at $\mathrm{p}\mathrm{H}=5$ $$ ? 

The number of chiral centres in penicillin is 

The volume (in $\mathrm{m}\mathrm{L}$ ) of $0.125\mathrm{M}{\mathrm{A}\mathrm{g}\mathrm{N}\mathrm{O}}_3$ ${}_{}$ required to quantitatively precipitate chloride ions in $0.3\mathrm{g}$ $$ of $\left[\mathrm{C}\mathrm{o}{\left({\mathrm{N}\mathrm{H}}_3\right)}_6\right]{\mathrm{C}\mathrm{l}}_3$ $\left[{\left({}_{}\right)}_{}\right]{}_{}$ is M $\left[\mathrm{C}\mathrm{o}{\left({\mathrm{N}\mathrm{H}}_3\right)}_6{\mathrm{C}\mathrm{l}}_3\right]=267.46\mathrm{g}/\mathrm{m}\mathrm{o}\mathrm{l}$ $\left[{\left({}_{}\right)}_{}{}_{}\right]$

${}^{\mathrm{M}}{\mathrm{A}\mathrm{g}\mathrm{N}\mathrm{O}}_3=169.87\mathrm{g}/\mathrm{m}\mathrm{o}\mathrm{l}$

Two Zener diodes (A and B) having breakdown voltages of 6 V and 4 V respectively, are connected as shown in the circuit below. The output voltage V? variation with input voltage linearly increasing with time, is given by: (V_input = 0 V at t = 0) (figures are qualitative)

The number of bonds between sulphur and oxygen atoms in ${\mathrm{S}}_2{\mathrm{O}}_8^{-}$ ${}_{}{}_{}^{}$ and the number of bonds between sulphur and sulphur atoms in rhombic sulphur, respectively, are :

A parallel plate capacitor has plate of length ' $$ l', width ' w$$ ' and separation of plates is 'd $$ '. It is connected to a battery of emf V$$ . A dielectric slap of the same thickness 'd $$ ' and of dielectric constant $$ k = 4 is being, inserted between the plates of the capacitor. At what length of the slab inside plates, will be energy stored in the capacitor be two times the initial energy stored?